For decades, scientists studying a key climate phenomenon have been grappling with contradictory data that have threatened to undermine confidence in the reliability of climate models overall. A new study might settle that debate with regard to the tropical atmospheric circulation. The study addresses a major discrepancy between climate models and reanalyses regarding potential strengthening or weakening of the Hadley circulation in the Northern Hemisphere as a consequence of anthropogenic emissions. The Hadley circulation, or Hadley cell -- a worldwide tropical atmospheric circulation pattern that occurs due to uneven solar heating at different latitudes surrounding the equator -- causes air around the equator to rise to about 10-15 kilometers; flow poleward (toward the North Pole above the equator, the South Pole below the equator); descend in the subtropics; and then flow back to the equator along the Earth's surface. This circulation is widely studied by climate scientists because it controls precipitation in the subtropics and also creates a region called the intertropical convergence zone, producing a band of major, highly precipitative storms. Shown here: Clouds from deep convection over the tropical Pacific Ocean, photographed by the space shuttle. Such convective activity drives the Hadley circulation of the atmosphere.
Visit Website | Image credit: NASA